Ensure palette is always captured.

Author: JimBobSquarePants

src/ImageSharp/Formats/Tiff/TiffDecoderCore.cs

@@ -584,6 +584,15 @@ private void DecodeStripsChunky<TPixel>(
                 }
             }
 
+            {
+                // If the color decoder is the palette decoder we need to capture its palette.
+                if (colorDecoder is PaletteTiffColor<TPixel> paletteDecoder)
+                {
+                    TiffFrameMetadata tiffFrameMetadata = frame.Metadata.GetTiffMetadata();
+                    tiffFrameMetadata.LocalColorTable = paletteDecoder.PaletteColors;
+                }
+            }
+
             return;
         }
 
@@ -621,11 +630,13 @@ private void DecodeStripsChunky<TPixel>(
             colorDecoder.Decode(stripBufferSpan, pixels, 0, top, width, stripHeight);
         }
 
-        // If the color decoder is the palette decoder we need to capture its palette.
-        if (colorDecoder is PaletteTiffColor<TPixel> paletteDecoder)
         {
-            TiffFrameMetadata tiffFrameMetadata = frame.Metadata.GetTiffMetadata();
-            tiffFrameMetadata.LocalColorTable = paletteDecoder.PaletteColors;
+            // If the color decoder is the palette decoder we need to capture its palette.
+            if (colorDecoder is PaletteTiffColor<TPixel> paletteDecoder)
+            {
+                TiffFrameMetadata tiffFrameMetadata = frame.Metadata.GetTiffMetadata();
+                tiffFrameMetadata.LocalColorTable = paletteDecoder.PaletteColors;
+            }
         }
     }